Improvement in the manufacture of malleable iron and steel



UNITED 'STATES PATENT OFFICE.;

HENRY Bn'ssEMna, or LoNDoN, GREAT BRITAIN'.

IMPROVEMENT lN THE MANUFACTURE 0F MLLEABLE IRON AND STEEL.

Specification forming part of Letters Patent No. 51h/MDB, dated December 5, 1865.

To all 'whom yit may concern.-

Be it known that I, HENRY BESSEMER, of

Queen Street Place, New Cannon street, in the 'malleable iron and steel from pig or other car buret of iron by forcing atmospheric air into the molten metal, this method of operation being now generally known as the Bessemer process.

\Vhen steel or malleable iron is so made from pig-iron a. reverberatory furnace has generally been employed to meltthe crude metal, and it has been found that a loss in the original weight of metal takes place in such melting process,

and also that some of the carbon present in the iron is lost, while the proportion ofsulphur it contains is augmented.

y Now, therefore, the first part of my said improvements has for its object the lessenipg ot' the quantity ot'iron and carbon lostin the melting process, and also the lessening of the qua-ntity of sulphur absorbed, while, at the same time, the quantity ot'fuel consumed in the melting-furnace is diminished.

In order tov carry into practical operation this first part of my said improvements I ernploy a reverberatory furnace constructed in the manner usual for melting pig-iron, excepting at that end of it which is nearestthe chimney, where it is provided with a second hearth or chamber having a iat or nearly-horizontal bottom, through which the flames and heated products of combustion pass on their way to the chimney. This chamber may, if desired, be a simple elongation of the bank or part on which a portion of the metal is to be melted; but I prefer to separate the melting-chamber from the second chamber by a dip in the roof, so as to contract the aperture leading from the first to the second hearth. The bed of the second hearth may, if desired7 be made movable on wheels, so as to facilitate the removal of the pi gmctal and convey it to the convertingvessel.

In order that this combination ot' a meltingfurnace with a heutingchamber may be fully understood, l have given a longitudinal sec-A tion of such furnace at Fig. l on Sheet A of the drawings hereunto annexed, where a is the tire-grate; b, the bed of the furnace, where the molten metal accumulates, and c the bank on which the charge ot' pig-iron intended to be` melted is placed.

The additional heating-chamber d communieates with the melting-chamber by an opening at e and with the chimney fby an opening at g. The chamber (l extends downward to the floor-level, so that the carriage h may be readily moved in and out of the heating-chamber. Thiscarriageconsists ofanir'on fraine;i,mou nt ed on four wheels, two of which are shown atj. The upper part of the carriage-frame is recess'ed for the purpose of retaining the firebrick floor k, on which the metal to be heated is packed in such a manner as to admit of the passage of the heated products of combustion from the melting-chamber through or between it, as shown at u, whereby the metal placed on the bedl k may be highlyheated during thev will be necessary than issufficient to melt the charge of metal on the first hearth, and also that the decarbonization and absorption of sulphur will belcss in the unmelted portion of the charge than it is in the portion that has undergonel fusion. From one-third to one-half th whole charge may be thus heated without being melted in the furnace; but these proportions may be varied to suit the heat-producing quality of the iron when undergoing the converting process. -As soon as that portion ofthe metal occupying the tirst hearth or chamber is melted the metal occupying the second one will have be- I come highly heated, and may then be put into the converting-vessel while still in a solid state,

and the molten part of the charge be immediately run into the vessel with it, and the con-. verting-vessel may then be turned up and the forcing in of atmospheric air he proceeded wi th -in the usual manner ,or the unmelted portion of the'iron may be put into the converting-vessel "after the'jme'lte'd portionhas been 'run into the vessel or after itl has been partially decarbonized.

When steel is required the process may be arrested at that stage where thedesired amount 1 of dccarbonization has been arrived at, or the Y l and is now generally employed for that purpose. This carbureting or alloyin g metal may be put into the converting-vessel in a heated and unfnsed state or in a melted state, as generally practiced. It will nevertheless be understood that the metal heated in the second hearth may be of'the same'q-ualityas'that melted on the first hearth, or it may, it' desired, be of some other kind onqnality of -iron, either in a crude or in a refined, or partially rened, state, and although I'prcfer to economize fuel byheating the unmelted portion ofthe metal in the after part of the'samefurnace by means tite oresA-I prefer to melt theA better quality where such fluid iron from blast-furnaces can be conveniently obtained, and the inferior or -cheaper kinds of pig-iron to be mixed' therewith I tlrst subject to a refining process by any of the methods now in use for refining ycrude iron, or such inferior or cheaper quality of iron may beA purified-and retmeldmby` puddling it more orless, 'so that it may be brought nearly or quite to the point atv which the process is generally stopped when making pud-` usual when making wrought or malleable iron. This puddling or partial puddling of the metal in the converting-vessel may be performed by' it may be simplyeiected by hand-labor in the usual way. ,In either vcasethe metal thus puried or refined is to be put, while in a heated E of the charge, consisting of the molten carbu; ret of iron, is then t'o be run-in with it, andthe process of conversion by air proceeded with in- `the same manner as hereinbefore described. When heated pig-iron is employed in a solid state along with the fluid metal. y

Incarryinginto practical operation thiapart of=my said invention the inferior orcheaper kinds .of ironsuch as-are producedv from theblaek-band iron-stone or' from argillaceous and other ores of ironmay be employed in combination with other and pnrercarbnrets of iron a quality for which such cheap or inferior iron is' not so well adapted in its unrefined state;

of the waste heat of such melting process, Iasn and although the'pnddling or partial puddling hereinbefore described, it will nevertheless be understood that such metal may be heated inany other suitable manner, or the metal forming a portion of the charge may, if preferred, be used in less quantity withouty being heated at all previous to its being put into the converting-vessel. In either case the addition of sulphur thereto and the loss of carbon therefrom will be effected in a less degree than would resultl from the fusion' of the whole charge of metal in the reverberatory furnace, as heretofore practiced." t

I would here remark that in Letters Patent issued to me, No. 1 have referred to a furnace in compartments for heating and converting the same metal but important advantages will be secured by performing both these operations in the same compartment of a suitable vessel. Among these advantages are that, if desired, such vessels may be readily mounted on an axis, and the construction is also sini- -pler and more convenient. v I

When it is desired to employ a carburet of iron of a cheap or inferior quality-such as is usually made from the black-band or argilla-- ceous ores-alongwiththepurerkindsofironsuch as are obtainedfrom v'spathose or hemaotl such cheap or inferior kindsof iron may' be performed byvmanual labor in the ordinary way it.will be obvious that the metal may be more cheaply and advantageously. vrefined in arrangements ot'. mechanical puddling apparatus in which that process is .ei'ected-in arevolving cylinder or otherwise. I- prefer that ofthe puddling process at which it has the general properties of steel, or it may, if preferred, be carried on until its .complete decarlbonization is effected. `In either case it may he roughly balled up for convnience of removal whilel still in a heated state to thaconvertin g-vessel, or it'may, if preferred, be mixed' withthe molten iron in a loose granular state, withontballing it up. j

The molten crude iron which I prefer to employ in combination with the puddled metal is highly carbureted, being of the quality known as N o'. 1,- since this quality of metal will furnish suicient heat to melt down a considera# ble quantity of the puddled metal, especially if the latter be not entirely decarboniied and is put into the converting-vessel in a highlyheated state. Frein one-fourth to one-half,

of iron in a reverberatory furnace, as 'heretofore generally practiced, exceptin those cases died steel, or it may be carried lto the extent prior to. its mixture with a carbnret of iron' any known mode of puddlingmechanically or state, into the converting-vessel, and the rest l inthe production/otl` steel or malleable iron ot' largeqnantities by some of the Well-known the metal should be carried 'to about that stage more or less, of .the'puddled metal may be employed, at the discretion of the manufacturer; but this may be much varied.

The converting vessels mounted on axes, such as are now generally employed for converting crude molten iron into steel or into malleable irou by the Bessemer, process, are generally heated to a very high temperature previous to running the fluid metal therein, and it has been the general practice to continue the combustion ot' fuel in the v'essel duriu g the whole or a great part of the time occupied in melting the charge of pig-iron in a reverberatory furnace, which is intended tobe converted therein. a

Now, the object of the second part of my said improvements is to eeonomize the fuel so used and at 'the same time to lessen the wear and tear of furnaces by employing the converting- .vessel as a heatiu g or melting vessel, wherein the metal to be converted maybe highly heated while in the solid state or be wholly or .in part melted therein, and he, without removal from the vessel,a't once converted into malieableiron or steel. When solid fuel is to be employed for this purpose a tire may be lighted in the converting-vessel and a moderate blast may be employed until it is well ignited. The carburet of iron, whether in the state of pig-iron or, rellned in any way, is to be thrown upon the iuel und the blast then urged `until the metal is very highly heated. l

Thismodeofheatingt-he metalmaybe readily understood by reference to Sheet A ofthe. annexed drawings, whereFig. 2 is a vertical section ofa coilverting-vessel, such as is now generally employed in the manufacture of steel by the Bessemer process, and such as has been described in my previous patents.

lt will be perceived that the fuel m,`lyiug over the numerous orifices ofthe tu yeres n, will be highly ignited by the powerful blast issuing from thcnnand consequently thelumps o fmetal p will acquire a very high vtemperature by the `time the vessel has been sufticiently heated.

It is desirable to use no more fuel than willV sutlice by its combustion tp heat the vessel and the metal suicieutly, or there may be some ditiiculty in removing the unconsumed fuel which tloats on the surface ofthe metal which is afterward putin.

When the metal is suicieutly heated the vessel is then to be turned into a position to receive some` molten carburet ot' iron, which may then be run in from any suitable meltingfurnace, blast-furnace, orladle. When this is done any fuel still remaining unccnsumed may act upon.

sparks thrown out of the mouth ofthe vesselindicate the 'counm-ncement of fusion. At this stage of the process the vessel may be partly turned ldown, so-that the drops ofv fused metal will not accumulate over the orifices of the tuyeres, hut will occupy the same part of the vessel' which a charge of iron usually occupies when first run i-uto the vessel.' This position ofi the vessel and its contents is shown in vertical. section at Fig. 3 on the annexed Sheet A of drawings. In order to eil'ect this fusion of the metal withoutany undue oxidation thereof, I prefer to divide the tuyere-box or make separate tnyere-lmxes,so that the blast of air employed to urge the tire may he conveyed only from those tuveres that are below the fuel when the vessel is partly turned down, as before described.

I may here remark that separate and d ivided tuyere-boxes have been shown in 'prerions patents of mine, but were there shown as used fora different purpose.

In Fig. 3 of Sheet A of the drawings annexed the tuyere-box r is shown with a division-plate, s, formed therein, so that the blast of air may be admitted to each compartment of the tuyere-box when necessary by pipes the fusion of the 'tnetal commences the vessel -should be turned .on its axis until it assumes the position shown in Fig. 3, and the supply of air should then be turned off by a suitable valve from the pipe t, and consequently be prevented from passing through the tui eres e, where there would be little or no fujel i'or it to The communication with the blastengine is, however, still to be kept up by means of the`pipe u, which enters the lower part of the tuyerebox and admits a powerful blast 'through the lower set of tuyeres w, and will act ou the fuel which will have fallen in front of theseI tuyeresl solnewh t into the position shown at a'. The iiame thus produced will rapidly bring about the fusion ot' a part orthe whole of the charge of metal shown at y, the fused portion of which is also shown accumu- -lating at z, where it willbe still subjected lo the action otl the flame and heated products of combustion, and its temperature ,be thus kept up, although it is at too low a level to use above the orifices of the tuyeres.

Assoon as the whole or a sutlicieut quantity of the charge of iron is meltedA I prefer to remove as lunch as possible of the uneousumed fuel, which will be found iioating ou the surface of the Huid metal and nearly on a level with the mouth ofthe vessel. raked forward and allowed to fall out onto the iloorof the casting-pit-,and iftheblast beturned on at full pressure from the upper set of tuyeres while the vessel is still in the position shown in Fig.3, any remaining portionsof thefuel will be blown out of the mouth of the vessel, after which the vessel may be turned up and the conversion of the metal effected by fomin g atmospheric air The fuel may be or connection with a gasometer.

into and below the surface'thereof,'as now generally practiced, the charge of metal so treated The 4fusion of. the metal may; he effected by coke as much freed from sulphuraspossihle,.

or any purer fuel capableoff-git-ing sutiicient -heat may be employed in lieu thereof.

When cons'enient the gases from the blastt'u'rnaces' may be employed, or carbonio oxide or carbureted hydrogen or mixtures thereof may be employed to heat or melt the metals in the converting-vessel, in order tov prepare such metal for conversion. I prefer to convey jets oi combustible gases and atmospheric air into the vessel through the tuyeres forthe purpose of heating or melting in the converting-vessel a portionor. the whole ot' the metal that is to he converted -the rein;'b ut these jets may be conveyed through tuyeres-placed elsewhere.

I prefer to make a-divisin ot' the tuyerebox o'r boxes in -such a manner las will admit of streams ofairand streamsof gas heilig directed' into the vessel through the tuyeres, or the airand gases may be conveyed into the vessel through separate tuyeres and tuyere-boxes, so. .as-te cause a cempleteccmhustion of thegases, but whichshall nevertheless becapable ofsuch regulation as willprevent any undue loss of metal from oxidation.

Both the air and gases may. if desired, he employed in a heatedfstate, and when thus applying gases through the tuyeres separate communication may liefniade for them through the axes of the vessel, or a temporary communi-` cation may be established by a movable pipe 'ln order thatthis mode of hea-tingor melting metal hy'gas in the converting-vessel prior to the conversion of such metalmay befnll y under-,1 stood, I have shown at Fig. 4 of Sheet A of the annexed drawings a vertical` section of a tuyerebox having a division-plate, A, therein, as beforereferred to. This plateis provided with' a series ot' conicaly openings which'are' placed opposite to a similar set of openings formed in theupper part, B,. ofA the tuyere-box B. The tuyeres C have an elongated partat U, which passes -throngh'th'e epehings in 'the' plate A,f and is kept air-tight therein by ramming some-y clay into the joint around the lower end ofthe tuyere. Every alternate hole in' the tnyere should have another hole (1" made in it at right angles to the main passage which passes longitudinaliy through it, the bottom ends of each such passage being plugged with clay, whereby all such passages through the tuyere may he made to convey gas from the upper or gas chamber l) of the'tuyere-boxinto the vessel, but can convey no air from the lower .or air chamber-,13, in consequence of the lcv. er ends of such passages being plugged, while all those longitudinal passages in the tuyei'e ,which have n o cross passage communicatin g .with -the upperor gas will convey atmospheric air into the-vessel. By thisarrange'ment each tuyere willsomewhat resemble an Arg'aud gas-burner with air and gas issuing from alternate holes around its outer edge. A horizontal section of such a ,.tuvere isshown .atFig-.- 5, i

'rate streamsthroughfthe tuyeresJ-into'the vessel wil lproducean intense combustion and rapy idly heat 'or melt themetal therein, the quansteel. .As now generally practiced, the tuyeres project upward. fromthe tuyere-box into the vessel, and the spaces between them are filled up with a mixture of powdered ganister and water havingy the consistencyrof batter. As much as fifteen or twenty gallons are sometimes used, and it has'been found to occupy an inconvenient amount ot' timeand expenditure ot1 fuel to evaporate the water from this semifluid matter. I therefore perforate the lower plate of the v.con vertingeressel vand i. put-en it felt or some woven fabric capable ot' allowing the water to drain through; or, if the perforations in the plate are very small, the water will drain through the plate without the addition of any other porous substance. Iprefer to assist the extraction of the' water by means of a partial vacuum formed by an exhaustpump connected with the un der side ot' the perforated plate, an airtight joint around the upper part ot' the tuyere-box being made by a turned ring Aot' metal or vby india-rubber or other suitable connected to the tuyere-box by a movable pipe or the blast-engine employed to force Lair into the metal inayhave the Valves soarranged as tov renderitcapable of acting at any time as anl 'exhaustipump.v 'In either case a receiver should be placed on the exhaust-pipe into which the water would flow instead of going .into the exhaust-pump; and although I have explained vhow the drying of the material occupyingv the xspaces netweefnfthe tuyeres maybe facilitated therefrom, I.. lueyertheless desire it to befun- `densto'odv that this. application ofthe exhaust.y

dry material, such las coarse sand, gansterfor other refractory material in a state 0f. powder, the pressure otair on the upper surfaceefthe mass holdin g it firmly in place until the heat and sla-gs have .s-uticientlyeonsolidated its surface, and ,by this means the, setting ottuyeres lwill be greatly expedited.' t It has hitherto' bcenfthe generalpraetice to so connect' the tuverehox toI the convertingchamber, D, and are'open atltheir lower ends T'llhis modelofsupplyingiairand sepaployed in the manufacture of malleableiron and packing. A small exhausting-pump may be by drawing off alarge portion of the'water pump enables me to use a nearly or perfectly lower part of the converting-vessel.

. of the converting vessel.

through the plate 4. This plate is secured to.

vessel as to leave a space between them for the free escape of air should any portion leak out by the side ot' the tuyeres, a provision which it is important to retain'. is intended to apply the 'principle of exhaustion tothe removal of water from the semitluid materials run in between thetuyeres, I Dso arrangethe closing up of this space that when the drawing olf of the water has been eiiected the space forthe escape of air from leakage may` again be readily opened.l The mcdeuby which I eiect this object will bebetter understood by reference to Sheet B of the drawings hereto annexed, where Fig. Gis a vertical section through thetuyere-box and a portion of the 1 is the tuyere-box secured by studs to the lower part These studs pass the tuyere-box at several places by bolts.- The plate 4. is perforated and has upon it a piece of felt or wire-gauze or other pervious woven fabric, in which holes are cut for the tuyeres 6 to pass through, and which will prevent the solid particles of ganister or sand from passing through the perforations in the plate tpalthough it will allow the passage of water fromthe/semi-iuid mass which is shown at?, and which lfills the spaces between and 'around .the tuyeres. The outside of lthe tuyere-b'ox is turned'truly to t the inside of the ring of metal '8. The upperpart of this ring is made true,orvit may be covered with some elastic material, so as to make a nearly close or airtight joint with the plate 4. There are vertical ribs atintcrvals formed around the inside of the upper part of the rings, so as to guide it up and down steadily on the outside of the tuyere-box. These ribsdo not obstructthe communication between the space l0 and the annular space 9 which "surrounds the tuyerebox, and into which a pipe,.1l, is fitted. lThis pipe may be unscrewed so soon as the withdrawal of the water is effected. Ihe' ring 8, when in use, is forced upward in contact with the plate 4 by several screws, l2, which pass through lugs 13, cast on the tuyerebox. The

withdrawal of these screws will allow the ring 8 to sink down onto the lugs 13 and again open the space 10, so that any airthat may leak from thetuyerebox around the tuyeres may escape freely.

The loss of time occasioned by the drying oftuyer'es set in the manner herein first de- .scribed will be for the most part prevented by providing several tuyere-b'oxes or tu yer'e-plates through which the tuyeres project. A raised conical ring may be placed around them, and the spaces between the tuyeres rammed up with ground ganister or 'other material and then baked dry. The ring maybe then removed, and in that dry state 'they may be put into the vessel. I prefer that a hoop of iron ora ring of brick-work should be placed around the lower part of the vessel for the purpose of defining the size' of the opening left by the removal of When, therefore, it'

Imass shown in Fig. Scan be removed.

may be tilled with ganister mixed with water run iu from the top, or preferably from an opening on the outside of the vessel, or the space may be filled with dry sand or other material.

This mode of buildingup andbaking a set v of tuyeres in a tuyere-box-previous to puttingA them into ,the convertingvessel will be better understood by reference to sheet B of thedrawin gs hereunto annexed,which shows the methed I prefer for carrying out this part of my invention.

Fig. 7 is a section of a tuyere-box and the lower part of the converting vessel. The t-uyere-box with the tuyeres built up and ready for inserting into the vessel is shown in elevation at Fig. 8.

The tuyere-box Gis, as usual, provided with a plate, H, with an interval for the escape of air in case of leakage. To vthe plate H a conical ring of thin iron, I, is fixed, which serves to retain the materialwhich occupies the space lbetween and around the tuyeres. This matcrial,which consists generally of ground ganister moistened 'with water, is to be rammed i-nto the space included within the ring I,and is also to be carried up' at the same angle as high as the top end ofthe tuyeresand it may then .be slowly dried or baked. When inserted in the lower part of the vessel a space, J, will be left,whi'ch is to be tilledvwith a semi-liquid mixture of ganister and water, which may be run in in the way generally practiced when setting tuyeres. The water from this small portion -will be soon absorbed by the dry surrounding materials, and the vessel will thus, in a short time, be in a condition suitable .for the con-v When worn out the whole The verting process.

conical ring K (shown in section at Fig. 7, and

which is bolted to the lower part of the vessel) will determine the line of separation of the materials when the tuyere'- box is removed. I,

however, desire it to be understood that I do not claim the removal of the whole bottom of the vessel with the tuyeres-therein, because this has already been practiced.

The'tuyeres used in the manner hereinbefore described sometimesbreak transversely and-the air, by getting inte the crack, forces the upper end of the tuyere into the metal and causes the lower part of the tuyere to'quickly wear away. To prevent this I make a somewhat larger hole in the center of the tuyere,

roughened or corrugated throughoutits length, and into this I insert an iron bolt or rod, also roughened lor formed with rings on its surface.

'I then pour some cement into the space formed between it and the inside of the tuyere-holes, so that the tuyere may be eifectually heldin place even if a fracture should take place. A longitudinal section cfa tuyere so constructed is shown at Fig. 9 on Sheet A of the annexed drawings, Where N N show the lairpassages and B the corrugated or ribbed iron rod or bolt "put, into the corrugated central opening, and

then run in with amixture of Portland cement. land ground irebrick,or.with other suitable cementf a A1n the mauufactureof malleable iron and steel'froin crude iron'or from refined or partially-refined iron byforcin g atmospheric air into and below thesurlace'of the iuidmetal,

air with-the'vapors of acids, alkaline, or saline fluids vor ,hyd-rocarbons, or 4by passing the air .throngli'or between any solid substances capablezofgivaporizing or in part vaporizing or alteringethe' properties of the air with a view to act upofnio'r. combine with'thesubstances present i'nthe .crude metal, and thus further refine, pu-

rify, =or improve its quality. The air and the liuid y or solid .substances among which it is passed may be either in a cold orin a heated state, as may be found preferable.

In carrying this system into practical oper? ation l lprefer to line the lower part of the airreceiver, which is in communication with the blast-engine, with lead or with pottery-ware, or with other substances not easily destroyed by the 4iuids'to 'be employed therein, the air from the blast-engine bein gconveyed through perforatio'us situated below the surface of such fluid, and Ybeing allowed to bubble up through it, and thusbecome more or less altered in its properties andy chemical constituents prior to its passage through the tuyeres into the molten metal.

. I desire. it to lbe understood that I dovnot claim as my invention the employment of any vspecial fluid matters through which the air is' to be :passed or to become impregnated with, as the same will depend on the nature of the substance contained in the iron which it is intended to act upon, or Whether such alteration of the constituents of the air is effected for the purpose of increasing the temperaturel of the contents of the converting-vessel, or for so combining with the oxygen contained therein -as better to adapt the air for use, as a means What I- claim inthe manufacture otmallew ble iron and steel and in the apparatus elnlployed in such manufacture isu 1. In the manufacture of malleable iron and steel, the employment, in theeonverting-vessel, of aportion of the charge of pig or refined iron in a solid and unmelted state when placed to be heated and converted in the same compartment of such vessel in combination with another portion of crude iron in a fluid state, in the manner and for the purposes described.

2. In the manufacture of malleable iron'an'd s teel, the employment, in any suitable vessel, of a portion of the charge'of pig or refined iron in a solid and nnheated state in combination with another portion of crude iron in a fluid state,"substantially inthe manner and for the purposes described. v

3. The manufacture of cast-steel andcast u malleable ironvby mixing andcombixnlg molten carburet of iron with other iron or steel which has been refined or partially refined by puddling, but which has not been manufactured into finished steel, where the fusion of such 4refined or partially-refined iron or steel is effected lby forcing atmospheric air or other gaseous matters into the saidfmolten earburet of iron.

4. Heating or melting iron inthe convertingvessel by heat derived from the fuel employed prepara-tory to the commencement of the converting process for heating or drying such vessel. v

5. 'The application to the heating or melting of iron in the converting-vessel either by solid or gaseous fuel of the vsame apparatus `which forces or conducts air or gases into such ves sel for the purpose of carrying on theconverting process therein. i

6. Constructing a tuyere-box in such almanl forated plate, either covered lor not covered with a suitable porous fabric or its equivalent, substantially as and for the purposes specified. l 9. The mode herein described of securing the tuyeres to the tuyere-box.

10. Using the ring K of any suitable material orv its equivalent for the purpose of defining the size of the opening of the line of fracture in that part of the converting-vessel where the tuyeres are inserted, substantially as det from aconverting-vessel without-,takin g off the bottom of such vessel, substantially as and for the purposes describe V.

12.: The employment of a partial vacuum for dryingor consolidating the materials employed in setting tuyeres in converting-vessels.

13. The mode, substantially as described, o f strengthening a tuyere by a central iron rod, and thus holding the parts thereof together when fractured. Y

Witnesses Taos. BROWN, DAVD. LoNGsDoN. 

